Foamed polystyrene trays are widely used in the packaging of edible products, such as meat, cheese and fruit. Typically, such trays are packaged on automatic equipment by wrapping the tray with a clear film. A persistent problem with such trays is cracking during the wrapping operation or afterwards, particularly in the corners of the tray. This necessitates using heavier gauge foam, an additional expense, or the use of special designs, such as disclosed in U.S. Pat. No. 4,058,247, which is incorporated herein by reference. In accordance with this invention, the cracking problem in such foamed trays is alleviated by using the polyethylene additive in the polystyrene foam.
Polystyrene foams containing low density polyethylene, especially suitable for formation of blow molded articles are described in U.S. Pat. No. 3,520,834 which is incorporated herein by reference in entirety. Foams of poly(para-methylstyrene) containing polyethylene homopolymers or copolymers are described in U.S. Pat. No. 4,255,531 which is also incorporated herein by reference. The purpose of the polyethylene in U.S. Pat. No. 4,255,531 is to enhance cross-linking when the composition is irradiated. It is not intended that the compositions of this invention be irradiated and they need not be so treated to be entirely effective for the purpose intended herein.